Washington State Department of Revenue Sales Tax Rate API

The API provides direct access to the Washington Department of Revenue's address based rate lookup technology platform. As Washington state's principal tax collection agency, the Department of Revenue oversees about 60 different taxes. It collects more than 90 percent of state General Fund tax revenues and all local sales tax revenues. The rate lookup URL is designed to return the current sales tax rates for an address. The API uses RESTful protocol and responses are formatted in either XML or TXT.